This invention relates to a clamp for an elongate member.
An optical fiber comprises a core and a cladding, both made of glass. The diameter of an optical fiber is typically about 125 microns.
Optical fibers are rather brittle and cannot withstand considerable handling. In order to protect the fiber, it is usual to encase the fiber in a buffer layer of synthetic polymer material. The nature of the polymer material and the thickness of the buffer layer depend upon the use to which the fiber will be put. Thus, when the fiber is to be wrapped with other fibers in a cable, a buffer layer that is thin and hard may be adequate, whereas a thicker yet softer cladding may be appropriate when the fiber is to be used as part of a communication network in an office building and will receive fairly rough handling during installation.
Various tests are performed on optical fibers in order to ensure that they will meet specifications. Some of the tests are carried out using a test and measurement instrument that includes a camera. A length segment of the fiber is held in the test and measurement instrument by a clamp that grips the buffer layer at a location close to an end face of the fiber, and the clamp is mounted on the stage of the test and measurement instrument so that the length segment of fiber lies on the optical axis of the camera and the end face is presented toward the camera.
Known optical fiber clamps operate satisfactorily in a test and measurement instrument when the buffer layer is quite thin and does not undergo significant flow during the time taken to conduct a test. However, it is not satisfactory to clamp a fiber having a thick buffer of soft material in this fashion, because the buffer undergoes progressive deformation in the clamp and consequently the end face of the fiber moves relative to the optical axis of the measurement instrument.